Well shock device

ABSTRACT

A shock device for unplugging perforations in a well and the like which comprises a chamber of low pressure relative to the pressure adjacent the perforations, the chamber being suddenly openable to the pressure adjacent the perforations with a consequent shock effect on the perforations.

United States Patent Inventor Appl. No,

Filed Patented Assignee Marion D. Kilgore Houston, Tex.

June 27, 1969 June 29, 1971 Dresser Industries, Inc. Dallas, Tex.

WELL SHOCK DEVICE 1 Claim, 1 Drawing Fig.

U.S. Cl.....

Int. Cl

E2lb 43/25 Field of Search [56] References Cited UNITED STATES PATENTS2,729,292 1/1956 Hinson 166/63 2,361,558 10/1944 Mason 166/299 2,776,7151/1957 Fuson etal. 166/63 3,029,732 4/1962 Greene 166/63 X 3,372,7553/1968 Venghiaths 166/63 Primary Examiner-David H. Brown Allorneys-Robert W. Mayer, Daniel Rubin, Peter J. Murphy, Frank S. Troidl, Roy L.Van Winkle, William E. Johnson, Jr. and Roderick W. MacDonald ABSTRACT:A shock device for unplugging perforations in a well and the like whichcomprises a chamber of low pressure relative to the pressure adjacentthe perforations, the chamber being suddenly openable to the pressureadjacent the perforations with a consequent shock effect on theperforations.

PATENTEDJUNZSIBH 3.589.442

INVENTOR MARION D. KILGORE m MM A TTORNE Y grit-i WlELlL SHOCKDiEVll'ClE BACKGROUND OF THE lNVlENTlON Perforations are formed in theearth surrounding a well bore to facilitate the production of liquidsuch as oil therefrom or to facilitate the injection of a liquid such aswater into the earth to increase oil production in another well. ineither instance liquid is passed through the perforations, either towardthe well bore in the case of the producing well or away from the wellbore in the case of an injection well. Sometimes the perforations becomeclogged with solidlike materials thereby lowering the efficiency of thewell be it a producer or an injection well. in such a situation it isbeneficial to unplug the perforations and restore its originalefficiency.

l-leretofore clogged perforations have been unplugged by using equipmentgenerally known as perforation washers. This equipment is lowered intothe well on tubing. For example, in a producing well heated oil underpressure is passed through tubing down to the perforations and theheated oil, because of the pressure behind it in the tubing, enters theperforations to clean same. The use of perforation washers which requirethe introduction of tubing into the well for their operation involves asubstantial amount of expense and time because of the need for runningtubing down the well bore.

According to this invention, a device is provided which can be run downthe well bore on a cablelike support such as a wire rope. A shock isthen applied by the device to the perforations by suddenly reducing thepressure adjacent the perforations thereby unclogging the perforations.

Passing a tool down a well bore by means ofa cablelike support is muchfaster and substantially less expensive than running tubing down thewell bore for the same distance.

According to this invention there is provided a shock device for wellswhich comprises means for separating a section of the well whichcontains perforations from its adjacent upper and lower sections therebydefining an isolation zone, a chamber openly connected to the definedisolation zone, blocking means for preventing pressure from the definedisolation zone from entering the chamber, and means for releasing theblocking means to suddenly allow pressure from the defined isolationzone to surge into the chamber thereby creating the desired shockeffect.

By applying the device of this invention to a producing well avacuum-type shock is applied thereby tending to cause greater flow ofliquid in the perforations towards the well bore containing the shockdevice.

In the case of injection wells the shock action is the same, but sincethe injection liquid is traveling in the perforations away from the wellbore containing the shock device, the shock action tends to reverse theliquid flow direction in the perforations back towards the well borecontaining the shock device thereby backwashing the perforations.

Accordingly, it is an object of this invention to provide a new andimproved device for applying a shock effect to a well bore. it isanother object to provide a new and improved device for unpluggingclogged perforations in a well bore. it is another object to provide anew and improved device for backwashing injection well perforations. ltis another object to provide a new and improved device for uncloggingperforations in a well bore without the use ofa tubing string.

Other aspects, objects, and advantages of this invention will beapparent to those skilled in the art from the disclosure and theappended claims.

DETAKLED DESCRlPTlON OF THE lNVENTlON The drawing shows a deviceaccording to this invention.

More specifically, the drawing shows a well bore 1 lined with casing 2and having perforations 3% extending radially outward therefrom.

The device itself is composed of a chamber 4 the interior of .vnich isat a pressure lower than the pressure normally obtaining in the casingadjacent perforation 3. The pressure in chamber 4i can be atmospheric orhigher or lower as desired. Generally, the lower the pressure in chamber4 with relation to perforations 3 the greater the shock effect and thegreater the likelihood of unclogging the perforations.

Chamber 4 is a hollow cylindricallike shape of any desiredcross-sectional size and any desired length. The cross-sectional sizewill generally be that which will fit within the casing with someclearance on either side. The length can be any desired length, forexample from 10 to 200 or more feet depending upon the magnitude of theshock effect desired.

' Although the device is shown inside a casing, the device could also beemployed inside tubing if desired.

Chamber 4 is supported by wire cable 5 which can be electricallyconductive if desired. Upper member 6 of chamber 4 can carry equipmentdesigned to facilitate the location of the perforations. A conventionalcasing collar locator and/or equipment desired for initiating operationof the device, e.g., conventional electrical means for receiving anelectrical signal by the way of cables and in turn generating anelectrical pulse capable of detonating an explosive as will be describedhereinafter in greater detail, can be carried on member 6.

Chamber 5 carries around its outer periphery and in spaced apartrelation means 8 for separating the section of the well bore whichcontains perforations 3 from adjacent upper and lower sections of thewell bore. The separating means 3 shown in the figure are conventionalpacker cups which are spaced apart along the length of chamber 4- todefine zone 9. Zone 9 encompasses perforations 3 and therefore isolatesperforations 3 from upper zone 10 and lower zone 11. Thus, zone 9 is adefined isolation zone.

Chamber ialso carries conduit means 12 which openly connects upper andlower zones 10 and 11 to allow the free passage of fluid therebetweenwithout entering zone 9.

Near the lower end 13 of the chamber, there is provided a plurality ofapertures 14 around the periphery of the chamber. These apertures aremeans for openly connecting isolation zone 9 with the interior ofchamber 4.

A blocking means 16 is provided in the interior of chamber llintermediate apertures 14 and the bulk of the interior of chamber 4. Theblocking means shown in the figure is a T- shaped piston. A lower endportion of the vertical leg 18 of T- shaped piston 16 threadably engagessleeve 17 which contains explosive charge 119. The lower end of sleeve17 is threadably fixed to protrusion 20 which is fixedly carried by end13.

Any conventional means for releasing piston 16 to allow pressure fromisolation zone 9 to surge through apertures 14 into chamber 4 and causethe desired shock effect can be substituted for sleeve 17. Sleeve 17 andexplosive 19 can be any conventional explosive releasing device which iselectrically connected by way of electrical conductor 23 to a firingdevice 24%, e.g., a step up transformer, carried on member 6. Firingdevice 241 can be electrically connected to cable 5 so that anelectrical signal can be passed down cable 5 to firing head 24 which inturn will generate the electrical pulse necessary to detonate explosive19 or a cap therein and will pass that pulse along conductor 23 toexplosive 19.

Other blocking means known in the art can be employed in the device ofthis invention.

in operation, for example in an injection well, water is normally pumpeddownwardly in casing 2 and radially outwardly from the well bore intoperforation 3 in the direction shown by arrow 25. One or more ofperforations 3 can become blocked by solid material 26 thereby reducingthe efficiency of the injection well by reducing the amount of waterinjected into the earth. The device of this invention is lowered intothe casing so that packer cups 8 straddle perforations 3, fluid pressurein zones lit) and ii forcing packer cups 8 outwardly into contact withthe casing 2 thereby isolating zone 9 from zones 10 and ll. The pressureinside chamber 4 is substantially atmospheric while the chamber in zone9 is at least p.s.i.g'. greater than atmospheric because of thepressurization of the water in the casing to cause same to enterperforations 3. Bypass 12 allows the lowering of the device in a casingfull of liquid.

After the device is set to form isolation zone 9 as shown in thedrawing, explosive 19 is detonated by sending an electrical signal downcable 5 as described hereinabove.

When explosive 19 is detonated piston 16 is freed and is very rapidlypushed upwardly to the upper end of chamber 4 by the higher pressurefluid, e.g., water, in zone 9 and perforations 3 acting throughapertures 14 against piston 16. The sudden upward movement of piston 16causes a vacuum effect by the great inrush of water through apertures 14which in turn causes a reversal of the direction of flow of water inperforations 3 as shown by arrow 28. This reversal in direction of waterflow in perforations 3 backwashes the perforations and forces obstacles26 out of the perforations into zone 9 thereby clearing theperforations. The device is then removed from the casing and theinjection procedure carried on at normal efficiency.

Reasonable variations and modifications are possible within the scope ofthis disclosure without departing from the spirit and scope ofthisinvention.

The embodiments of the invention in which I claim an exclusive propertyor privilege are defined as follows:

1. In a shock device for wells,

means for separating a section of the well from adjacent sections todefine an isolation zone, a chamber,

said well section isolating means being spaced apart packing meanscarried by said chamber,

means for openly connecting said defined isolation zone and saidchamber,

said means for connecting said defined isolation zone and said chamberbeing a plurality of apertures around the periphery of said chamberbetween said spaced apart packing means,

blocking means for preventing pressure from said defined isolation zonefrom entering said chamber, and

means for releasing said blocking means to allow pressure from saiddefined isolation zone to enter said chamber.

1. In a shock device for wells, means for separating a section of thewell from adjacent sections to define an isolation zone, a chamber, saidwell section isolating means being spaced apart packing means carried bysaid chamber, means for openly connecting said defined isolation zoneand said chamber, said means for connecting said defined isolation zoneand said chamber being a plurality of apertures around the periphery ofsaid chamber between said spaced apart packing means, blocking means forpreventing pressure from said defined isolation zone from entering saidchamber, and means for releasing said blocking means to allow pressurefrom said defined isolation zone to enter said chamber.